Light projector



Get. 13, 1931. M. EXELMANS 1,826,927

LIGHT PROJECTOR Filed NOV. 50, 1929 4 lNV ENTOR Jfuouw Mrwawm/ ATTORNEY Patented Oct. 13, 1931 UNITED STATES PATENT OFFICE MAURICE E XELMANS, F PARIS, FRANCE, ASSIGNOR TO HOLOPHANE COMPANY, INC., OF NEW YORK, N. Y., A CORPORATION OF DELAWARE LIGHT PROJECTOR Application filed November 30, 1929, Serial No. 410,669, and in France December 5, 1928.

The present invention relates to light projectors, and is more particularly directed toward light projectors adapted for using electric lamps having rectilinear filaments of large dimension. I

The present invention contemplates a light projector having one reflecting portion of comparatively small radius, generally in the shape or form of a fragment of a cir- 11) cular cylinder with its center or axis coinciding with a rectilinear lamp filament. The circular portion extends substantially 180 and is associated with a second reflector of different outline and greater radius of curvature extending beyond the edge of the circular portion of the main reflector and adapted to handle direct and reflected light.

A prismatic plate of lenticular form, placed with one free edge adjacent the edge 513 of the circular cylinder, has prisms adapted to refract and concentrate the rays it receives directly from the. lamp, and where desired the prism formation and circular reflector may extend far enough so that the prismatic 2.25 plate refracts and concentrates additional direct and reflected light, so as to produce a concentrated light beam in the desired direction. Considerable space is provided between the light controlling plate and the other edge of the circular reflector, and this allows direct light as well as some of the reflected light from the cylindrical reflector to pass out to the auxiliary reflector. This auxiliary reflector handles the light received by it so as 2.; to redirect it into such d rections as are determined by its configuration, which may be parabolic or hyperbolic or otherwise, depending on the manner in which it is desired to handle the light.

The accompanying drawings show, for purposes of illustrating the invention, several of the many possible embodiments in which the present invention may take form, it being understood that the drawings are illus- 15 trative of the invention rather than limiting the same.

In these drawings:

Figure 1 is an elevational view of the light projector,

L.) Figures 2 and 2a are diagrammatic sectional views taken in a plane at right angles to the lamp axis and illustrating a projector employing a parabolic auxiliary reflecting surface;

Figure 3 is a view similar to Figure 2, the auxiliary reflector being plane;

Figure 4 is a view similar to Figure 2, the auxiliary reflector being one composed of a combination of elliptical contours extended down to include all of the direct light from the lamp; and

Figure 5 is a fragmentary sectional view showing a detail.

In the forms shown in Figures 1 and 2, the projector is made up of a cylindrical reflector of circular cross section C having an opening approximately 180 from the point 0 to c, a cylindrical reflector of parabolic section P adjacent to the circular reflector at 0 with the focal line coinciding with the axis 0 of the circular reflector which is suificiently near to that axis, and a rectangular prismatic plate A with its inside edge adjacent to the edge a of the reflector C. This lens plate is disposed at a convenient angle, for example in relation to the opening 0 c of the semi-circular reflector. Window F between the edge a of the prismatic plate and the free edge I) of the parabolic reflector P is open or may be closed by a glass plate F having parallel faces, as indicated in Figure 2a. The reflectors P and C can be of any material, polished metal, prismatic or silvered glass.

The light source consists, for example, of a lamp having a rectilinear filament S of large dimension, is made so that the filament coincides as closely as possible with the axis 0 of the circular reflector.

The rectangular glass plate A receives direct rays from the source emitted in the sector aO'c and, after reflection, the rays emitted in the sector a'O-c. This plate A concentrates these rays into a laterally open flat beam. Parabolic reflector P receives, in addition to the rays emitted directly from a light source in section a-O-c', those reflected by the reflector C in sector cOa. Parabolic reflector P, if its focal line coincides with 0, sends these rays back in the form of a laterally open flat parallel beam through the window or opening F. Under these circumstances, the projector ives parallel or substantially parallel flat ams, as indicated in Fi ure 2.

arabolic reflector P may be hinged at c in relation to the circular reflector. Under these conditions one can adjust the parabolic reflector about the axis 0--c' and separate the light into two beams, one furnished by the plate A and the other by the reflector P, as indicated in Figure 2.

In the form of construction illustrated in Figure 3 the auxiliary reflector P is made plane, this plane being an ap roximation to a portion of a hyperbola. t redirects the re s as indicated.

igure 4 shows a construction in which the auxi iary reflector R is a combination or elliptical contours extending down to include all the direct light from the lamp which is not included by the lens and circular reflector. In such a combination the general distribution of light would be toward the right instead of toward the left. With this construction one would preferably use a lens plate A designed to redirect the light toward the right as indicated.

Light collecting devices of the type above described are more particularly designed for lighting showcases, pictures, black boards, corridor wall lights, and the like Where a comparatively small trough is desired.

It will, of course, be understood that the roportion shown in thedrawings are merely lllustrative, and that various distributions of light may be had b varying the an ular position and extent 0 the circular reflector and the prismatic transmitter as well as the form of the latter.

I claim:

1. A light projector comprising a rectilinear light source, a cylindrical reflector, a

ortion of which is generated .by moving a ine parallel with the light source and about a circular arc, whose center coincides with the light source, and another portion merging with the edge of the first portion and extending beyond said portion, and a prismatic plate extending part way across the opening formed by the opposite edges of the reflector and with one edge adjacent to the outer ed e of the circular portion of the reflector, tfie plate bein adapted to redirect direct light rays inclu ed by it, and the extended portion of the reflector bein adapted to redirect direct light received LEIOIH the source and reflected light received from the circular reflector.

2. A light projector comprising a rectilinear light source, a cylindrical reflector, a portion of which is generated by moving a line parallel with the light source and about a circular arc, whose center coincides with the light source, and another portion merging with'the edge of the first portion and having lens a parabolic contour, and a prismatic plate extending lpart way across the o ening formed by t e opposite edges of the re ector, and with one edge adjacent to the outer edge of the circular portion of the reflector, the plate being adaplted to redirect direct light and reflected lig t from the circular portion of the reflector, the parabolic portion being adapted to redirect direct light and reflected light from another part of the circular reflector.

3. A light projector comprising a circular cylindrical reflector, a rectillnear light source at the center of the reflector, a lens plate havin one edge adjacent an edge of the circular re ector and extending parallel with the light source and adapted to receive direct light, and redirect it in predetermined directions, and an auxiliary reflector disposed in planes parallel with the light source and extending from the opposite edge of the circular reflector and adapted to redirect direct light and 1i ht received by reflection from the circular re ector.

4. The combination with a rectilinear light source of a circular cylindrical reflector, a rectangular lens plate adjacent to one edge of this reflector for acting on direct light to form it into a laterally open flat beam, and an auxiliary reflector of cylindrical shape and at a greater distance from the light source and having a free edge spaced from the other edge of the lens plate, the auxiliary reflector acting on substantially all the direct and reflected light not utilized by the lens plate or escaping through the opening between the lens plate and the auxiliary reflector to redirect it in the same general direction.

5. The combination with a rectilinear light source of a circular cylindrical reflector, a rectangular lens plate adjacent to one edge of this reflector for acting on direct and reflected light to form it into a laterally open flat beam, and an auxiliary parabolic reflector having a free edge s aced from the other edge of the lens late, t e auxiliary reflector redirecting substantially all the direct and reflected light not utilized by the lens plate or escaping through the opening between the plate and the auxiliary reflector into a beam substantially parallel with the light from the lens.

6. A light projector comprising a rectilinear light source, a light transmitting and controlling plate having prisms parallel with one another and the light source for receiving direct light emitted in a predetermined sector about the light source and redirecting it in a laterally open flat beam at a predetermined angle to the plane of the plate, and light controlling and reflecting surfaces generated by the movement of a straight line parallel with the light source from one edge of the prismatic plate about the light source to substantially the plane of theplate at a point spaced from the light controlling prisms to provide a long wide aperture for the emission of light reflected by the reflecting surfaces, these surfaces being disposed so as to direct such light in directions substantially parallel with the main light beam from the prisms and spill the same to one side only by the main beam.

7. A light projector comprising a rectilinear light source, a light transmitting and controlling plate having prisms parallel with one another and the light source for receiving direct light emitted in a predetermined sector about the light source and redirecting it in a laterally open flat beam at a predetermined angle to the plane of the plate, and light controlling and reflecting surfaces generated by the movement of a straight line parallel with the light source from one edge of the prismatic plate about the light source to substantially the plane of the plate at a point spaced from the light controlling prisms to provide a long wide aperture for the emission of light reflected by the reflecting surfaces, these surfaces being disposed so as to direct such light in directions substantially parallel with the main light beam from the prisms and spill the same to one side only by the main beam, the length of the prisms reflecting surface and aperturebeing at least as great as the length of the light source and occupying the entire 360 about the light source so that all the light therefrom is emitted in a laterally openrfiat beam.

8. A light projector comprising a rectilinear light source, a light transmitting and controlling plate having prisms parallel with one another and the light source for receiving direct light emitted in a predetermined sector about the light sourceand redirecting it in a laterally open flat beam at a predetermined angle to the plane of the plate, and light controlling and reflecting surfaces generated by the movement of a straight line parallel with the light source from one edge of the prismatic plate about the light source to substantially the plane of the plate at a point spaced from the light controlling prisms to provide in directions substantially parallel with the .7

main light beam from the prisms and spill the same to one side only by the main beam, and a light transmitting glass closure for the aperture.

Signed at Paris, France, this 15th day of November, 1929.

MAURICE EXELMANS.

a long wide 'aperturefor the emission of light reflected by the reflecting surfaces, these surfaces including a substantially circularportion with its axis in the rectilinear light source and a substantially parabolic surface beyond the circular surface and being disposed so as to direct such light in directions substantially parallel with the main light beam from the prisms and spill the same to one side only by the main beam. '7

9. A. light projector comprising a rectilinear light source, a light transmitting and controlling plate having prisms parallel with one another and the light source for receiving direct light emitted in a predetermined sector about the light source and redirecting it in a laterally open flat beam at a predetermined 

